1. Field of the Invention
The present invention relates to a continuous metal casting process and, more particularly, to a method of oscillating a mold of a vertical continuous caster for the purpose of production of a cast metal which is free of breakout, oscillation marks and other defects.
2. Description of the Related Art
In general, when metal is being cast in a continuous vertical caster, the mold is vertically oscillated while a mold powder is supplied to the melt in the mold so as to reduce friction between the mold surface and the solidified shell of the metal. The effect of the mold powder is closely related to the condition of oscillation of the mold, and it is necessary that the condition of oscillation is suitably controlled such that the mold powder is introduced at a proper rate into the boundary between the mold and the solidified shell.
The oscillation of the mold is usually effected such that the velocity Vm of oscillation of the mold follows a specific sine waveform, as for example, as shown in FIG. 3. It has also been proposed to oscillate the mold in accordance with a modified sine waveform as disclosed in Japanese Laid-Open Patent application No. 60-87955.
On the other hand, U.S. Pat. No. 3,494,411 discloses a method in which a longitudinally split open-ended water cooled mold is used, wherein the mold is oscillated not only in the longitudinal direction which parallels to the casting direction but also in a transverse direction perpendicular to the casting direction.
This method, however, cannot allow control of the rate of supply of the mold powder in accordance with the casting conditions, because the longitudinal and transverse oscillations are effected independently.